1. Field of the Invention
The present invention relates to wiper devices for reciprocatingly wiping, for example, the rear or front windshield or head lamps of an automobile, the sight glasses of some industrial equipments and so forth. More particularly, the invention is concerned with a wiper device having a rise-up mechanism.
2. Description of the Prior Art
Wiper devices have been known, each of which has a mechanism which, when the wiper switch is turned off, lowers the wiper blades to a position below the lower end of their wiping stroke. When the wiper switch is turned on again, this mechanism operates to raise the blades up to the operating position before wiping is commenced. This mechanism, therefore, is generally referred to as a "rise-up mechanism". Usually, this rise-up mechanism is used in a concealed-type automotive wiper device which is adapted to conceal the wiper blades below the bonnet when the wiper device is not used. The rise-up mechanism is used also in a wiper device for a power-driven automotive rear windshield adapted to be raised and lowered by remote control. Namely, in order to permit a smooth upward and downward movement of the power-driven rear windshield, the rise-up mechanism usually keeps the wiper blades away from the rear windshield and puts them into contact with the rear windshield only when wiping becomes necessary. The rise-up mechanism is used also in various equipments having power-driven windows to keep the wiper blades below or above the area to be wiped so as not to hinder the movement of the window panels. Thus, the term "rise-up mechanism" should be interpreted to also include a mechanism which keeps the wiper blades at a position above the upper end of the wiping stroke, when the blades are not in operation.
An example of a rise-up mechanism is shown in the specification of U.S. Pat. No. 3,253,206. This mechanism has a crank arm connected to an output shaft driven by a wiper motor through a worm gear having a center offset from the axis of the output shaft, so that a crank pin provided on the crank shaft moves along a non-circular path so as to move, when the wiper switch is turned off, the wiper blades to a position out of the area wiped by the wiper blades during the wiping operation. This rise-up mechanism, however, requires a complicated construction including a special eccentric blade driving mechanism and a solenoid-actuated clutch for controlling the switch.
Under this circumstance, there is an increasing demand for a wiper device having a rise-up mechanism of a simple construction.